Portion of a cover for an electron microscope



FIG. 1 is a front, top and right side perspective view of a portion of a cover for an electron microscope showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The long and short dashed lines immediately adjacent the shaded area represent the bounds of the claimed design while all other broken lines are directed to an environment and form no part of the claimed design. 

CLAIM We claim the ornamental design for a portion of a cover for an electron microscope, as shown and described. 